Bought this PCB off a friend of mine and he said it works. It was in a converted cabinet and was running Galaga in it. Appears to have a Midway Galaga connector and wiring but not sure.
I agree with audiominiman, since it looks like a International Scientific bootleg of Galaxian. Are you sure it was playing Galaga, not Galaxian? The PROM stickers suggest it could be either. There are also some alternate version of Galaxian out there, such as Galaxian X, Super Galaxians, etc.
Thanx guys, my friend said Galaga but prob was confused. I did find a pic of a Galaxian PCB that almost was identical to this one. If this board works what do they sell for usually??